Takedown pin for a firearm

ABSTRACT

A takedown pin for a firearm, having at least some of a head; a shank, wherein the shank extends from the head to a terminal surface; a projection extending from at least a portion of the terminal surface; a first groove or slot formed in at least a portion of the shank; a second groove or slot formed in at least a portion of the shank, wherein the first end of the first groove or slot is positioned at a spaced apart location from the first end of the second groove or slot; and a connecting groove or slot formed between the first end of the first groove or slot and the first end of the second groove or slot.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation-In-Part of U.S. patent application Ser. No.15/365,666, filed Nov. 30, 2016, now U.S. Pat. No. 10,101,107, issuedOct. 16, 2018, the entire disclosure of which is incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISC APPENDIX

Not Applicable.

NOTICE OF COPYRIGHTED MATERIAL

The disclosure of this patent document contains material that is subjectto copyright protection. The copyright owner has no objection to thereproduction by anyone of the patent document or the patent disclosure,as it appears in the Patent and Trademark Office patent file or records,but otherwise reserves all copyright rights whatsoever. Unless otherwisenoted, all trademarks and service marks identified herein are owned bythe applicant.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates generally to the field of firearms. Morespecifically, the present disclosure relates to a takedown pin for afirearm.

2. Description of Related Art

Various firearms comprise certain components that are held together byone or more pins being releasably secured within apertures of thevarious components. Certain such firearms are the AR-15 or M4, the FusilAutomatique Léger (FAL), and the Special Operations Forces CombatAssault Rifle (SCAR) style firearm.

By way of example, the AR-15 is based on the AR-10, which was designedby Eugene Stoner, Robert Fremont, and L. James Sullivan of the FairchildArmaLite Corporation in 1957. Today, there are numerous variants of theAR-15 that are manufactured by a number of companies. The AR-15 and itsvarious related derivative platforms are used by civilians, lawenforcement personnel, and military forces around the world.

One of the reasons for the AR-15's widespread popularity and usage isits modularity. The AR-15 can initially be broken down into two maincomponents, an upper receiver and a lower receiver. The upper receiverincludes two lugs, each of which includes an aperture formedtherethrough. The lower receiver includes cutouts for receiving the lugsof the upper receiver and appropriate apertures to be aligned with theupper receiver lug apertures.

When the upper receiver and the lower receiver are appropriatelyaligned, a pivot pin is slidably secured within the aligned aperturesproximate the front of the lower receiver and a takedown pin is slidablysecured within the aligned apertures proximate the rear of the lowerreceiver to secure the upper receiver to the lower receiver. Onceinitially installed within the appropriate apertures in the lowerreceiver, the pivot pin and the takedown pin each slide between a lockedand an unlocked position, but remain attached or coupled to the lowerreceiver via interaction of a spring biased blocking element and aprimary channel and primary recesses formed in the pivot pin and thetakedown pin.

Because the upper and lower receivers are secured with slidably movablepins, the upper receiver can optionally be pivoted on the lower receiveror removed from the lower receiver. This allows a user to access variouscomponents of the firearm more easily for cleaning and lubrication.Additionally, alternate upper receivers can be used with a single lowerreceiver or vice versa.

Turning now to the drawing Figs., FIGS. 1-9 illustrate certain elementsand/or aspects of a known, exemplary AR-15 upper receiver 10 beingattached or coupled to an exemplary AR-15 lower receiver 20, using aknown receiver pivot pin 100 and receiver take-down pin 200, to form afirearm 30.

The pivot pin 100 comprises a head 110 and a shank 130. The shank 130includes a shank portion 132 that extends from a planar terminal surface134 to a shoulder 112 of the head 110. In some embodiments, anintermediate portion 136, having a reduced diameter when compared to adiameter of the shank portion 132, is formed or disposed between theshank portion 132 and the shoulder 112.

The head 110 extends from the shoulder 112 to a crown 116. In certainembodiments, a face 114, which is parallel to the longitudinal axisA_(L), is formed or disposed between the shoulder 112 and the crown 116.A flat 118 is typically provided in a portion of the head 110. A surfaceof the flat 118 is generally formed parallel to a longitudinal axisA_(L) of the pivot pin 100 so as to allow the pivot pin 100 to beappropriately inserted within the lower pivot pin apertures 22 of thelower receiver 20.

A continuous, elongate slot 140 is formed in the pivot pin 100 andextends along the longitudinal axis A_(L) from the shank portion 132into the head 110. A detent 142 is formed proximate each end of the slot140.

The take-down pin 200 comprises a head 210 and a shank 230. The shank230 includes a shank portion 232 that extends from a planar terminalsurface 234 to a shoulder 212 of the head 210. In some embodiments, anintermediate portion 236, having a reduced diameter when compared to adiameter of the shank portion 232, is formed or disposed between theshank portion 232 and the shoulder 212.

The head 210 extends from the shoulder 212 to a crown 216.

A continuous, elongate slot 240 is formed in the shank portion 232 ofthe take-down pin 200, along the longitudinal axis A_(L) of thetake-down pin 200. A detent 242 is formed proximate each end of the slot240.

Generally, the upper receiver 10 includes an upper pivot pin lug 11having an upper pivot pin aperture 12 and an upper take-down lug 17having an upper takedown lug aperture 18. The lower receiver 20 includescutouts, recesses, ears, or areas for receiving the lugs 11 and 17 sothat the upper pivot pin aperture 12 can be aligned with the lower pivotpin apertures 22 and the upper takedown lug aperture 18 can be alignedwith the lower take-down lug apertures 28.

The receiver pivot pin 100 is usually maintained within at least one ofthe lower pivot pin apertures 22 via engagement of a detent pin 43within the slot 140 of the pivot pin 100. A detent pin spring 49provides a spring biasing force that urges the detent pin 43 into theslot 140. Once the slot 140 is engaged by the detent pin 43, the pivotpin 100 is slidably movable between a release position and a lockingposition, but is maintained within at least one of the lower pivot pinapertures 22.

When the pivot pin 100 is in the release position, the shank portion 132is outside of the cutout between the lower pivot pin apertures 22,sufficient to allow the upper pivot pin lug 11 to be positioned withinor removed from the cutout between the lower pivot pin apertures 22.Alternatively, when the pivot pin 100 is in the locking position (asillustrated in FIG. 4), at least a portion of the shank portion 132 ispositioned within each of the lower pivot pin apertures 22.

The detents 142 are formed so as to be engaged by the detent pin 43 atthe release position and the locking position. In this manner,additional frictional engagement is provided between the detent pin 43and the pivot pin 100 to further secure the pivot pin 100 in the releaseposition or the locking position.

Similarly, the receiver take-down pin 200 is usually maintained withinat least one of the lower take-down pin apertures 28 via engagement of adetent pin 41 within the slot 240 of the take-down pin 200. A detent pinspring 47 provides a spring biasing force that urges the detent pin 41into the slot 240. Once the slot 240 is engaged by the detent pin 41,the take-down pin 200 is slidably movable between a release position anda locking position, but is maintained within at least one of the lowertake-down pin apertures 28.

When the take-down pin 200 is in the release position, the shank portion232 is outside of the cutout or void between the lower take-down pinapertures 28, sufficient to allow the upper take-down pin lug 17 to bepositioned within or removed from the cutout between the lower take-downpin apertures 28. Alternatively, when the take-down pin 200 is in thelocking position (as illustrated in FIG. 4), at least a portion of theshank portion 232 is positioned within each of the lower take-down pinapertures 28.

The detents 242 are formed so as to be engaged by the detent pin 41 atthe release position and the locking position. In this manner,additional frictional engagement is provided between the detent pin 41and the take-down pin 200 to further secure the take-down pin 200 in therelease position or the locking position.

When the upper receiver 10 and the lower receiver 20 are appropriatelyaligned, the upper pivot pin lug aperture 12 is aligned between thelower pivot pin lug apertures 22 such that the pivot pin 100 can beslidably moved to the locking position and the upper takedown lugaperture 18 is aligned between the lower take-down lug apertures 28 suchthat the take-down pin 200 can be slidably moved to the lockingposition. Generally, attaching the upper receiver 10 to the lowerreceiver 20 is accomplished by first coupling or attaching, via thepivot pin 100, the upper pivot pin lug 11 to the lower receiver 20.Then, the upper receiver 10 is pivoted, via interaction between thepivot pin 100 and the upper pivot pin lug aperture 12, until the uppertakedown lug aperture 18 is appropriately aligned between the lowertake-down lug apertures 28 and the take-down pin 200 is slidably movedto the locking position.

The lower receiver 20, includes a pushbutton magazine release button 50found on one side of the firearm 30. Ofttimes, the magazine releasebutton 50 is at least partially protected by one or more ridges thatreduce the chances of inadvertent activation.

The magazine release button 50 typically includes an internal, aperture52 that extends through the entire magazine release button 50. Themagazine release mechanism typically includes a magazine release button50 that is coupled to a magazine release 55, which includes a magazineengagement projection 58 that releasably engages a portion of amagazine, when fully inserted within the magazine well of the firearm30.

The magazine release 55 includes a magazine release connection shaft 56that extends from one side of the magazine release. The magazine releaseconnection shaft 56 includes a threaded portion 57 that can be threadedlate engaged with the aperture 52 of the magazine release button 50.

A magazine release spring 59 typically provides spring biasing to themagazine release button 50, when installed in the firearm 30.

When the magazine release button 50 is depressed, the magazine release55 is urged outside of the magazine well, such that the magazineengagement projection 58 is withdrawn from an inserted magazine,allowing the magazine to be removed from the magazine well.

It should be appreciated that a more detailed explanation of thecomponents of the upper receiver 10, the lower receiver 20, the magazinerelease button 50, the pivot pin 100, and take-down pin 200,instructions regarding how to attach and remove the upper receiver 10and the lower receiver 20, methods for utilizing the pivot pin 100and/or the take-down pin 200, and certain other items and/or techniquesnecessary for the implementation and/or operation of the variouscomponents of the firearm 30 are not provided herein because suchcomponents are commercially available and/or such background informationwill be known to one of ordinary skill in the art. Therefore, it isbelieved that the level of description provided herein is sufficient toenable one of ordinary skill in the art to understand and practice themethod as described.

Any discussion of documents, acts, materials, devices, articles, or thelike, which has been included in the present specification is not to betaken as an admission that any or all of these matters form part of theprior art base or were common general knowledge in the field relevant tothe present disclosure as it existed before the priority date of eachclaim of this application.

BRIEF SUMMARY OF THE DISCLOSURE

Known takedown pins only allow for two positions, an engaged or lockedposition and a disengaged or unlocked position. There is currently notakedown pin that allows for an intermediate, partially engaged orinoperably locked position. Furthermore, the elongate slot of knowntakedown pins are closed on both ends and do not include at least oneopen or partially open end of the elongate slot.

In various exemplary, non-limiting embodiments, the present disclosurecomprises a takedown pin that provides not only slidable engagementbetween an engaged or locked position and a disengaged or unlockedposition (similar to known takedown pins), but also slidable engagementbetween an engaged or locked position and a partially engaged orinoperably locked position. In the partially engaged or in operablylocked position, the upper receiver 10 and the lower receiver 20 of thefirearm 30 are capable of being only partially rotated relative to oneanother.

In certain exemplary, nonlimiting embodiments, the takedown pin isslidably movable, along the longitudinal axis of the takedown pinbetween the engaged or locked position and the disengaged or unlockedposition. When in the engaged or locked position, the takedown pin canbe rotated to an alternate engaged or locked position, wherein thetakedown pin can be slidably movable, along the longitudinal axis of thetakedown pin, between the alternate engaged or locked position and thepartially engaged or inoperably locked position. In certain exemplaryembodiments, the takedown pin is rotated approximately 180° between theengaged or locked position and the alternate engaged or locked position(between the first channel and a second channel). In certain otherexemplary embodiments, the takedown pin is rotated approximately 90°between the engaged or locked position and the alternate engaged orlocked position (between the first channel and a second channel).

In certain exemplary, nonlimiting embodiments, the takedown pin isslidably movable, along the longitudinal axis of the takedown pinbetween the engaged or locked position and the disengaged or unlockedposition. When in the engaged or locked position, the takedown pin canbe rotated to an alternate engaged or locked position, wherein thetakedown pin can be slidably and rotatably movable, relative to thelongitudinal axis of the takedown pin, between the alternate engaged orlocked position and the partially engaged or inoperably locked position.In certain exemplary embodiments, the takedown pin is rotatedapproximately 90° between the alternate engaged or locked position andthe partially engaged or inoperably locked position.

In various exemplary, nonlimiting embodiments, the takedown pin of thepresent disclosure comprises a head; a shank, wherein the shank extends,along a longitudinal axis, from the head to a terminal surface; aprojection extending from at least a portion of the terminal surface; afirst groove or slot formed in at least a portion of the shank, whereina first detent recess is formed proximate a first end of the firstgroove or slot, and wherein a second detent recess is formed proximate asecond end of the first groove or slot; a second groove or slot formedin at least a portion of the shank, wherein a first detent recess isformed proximate a first end of the second groove or slot, wherein asecond detent recess is formed proximate a second end of the secondgroove or slot, and wherein the first end of the first groove or slot ispositioned at a spaced apart location from the first end of the secondgroove or slot; and a connecting groove or slot formed between the firstend of the first groove or slot and the first end of the second grooveor slot.

In certain exemplary, nonlimiting embodiments, the first groove or slotdefines an elongate, substantially linear first groove or slot thatextends along the longitudinal axis.

In certain exemplary, nonlimiting embodiments, the first groove or slotlimits the rotational movement and the longitudinal movement of thetakedown pin, relative to a lower receiver.

In certain exemplary, nonlimiting embodiments, the first groove or slotlimits the rotational movement of the takedown pin to 0°, relative to alower receiver.

In certain exemplary, nonlimiting embodiments, when the takedown pin isappropriately positioned within a lower receiver of a firearm, a detentpin positioned at least partially within the first groove or slotinteracts with the first groove or slot so that the takedown pin can berepeatedly urged between an engaged or locked position, wherein thefirearm is operable, and a partially engaged or inoperably lockedposition, wherein the firearm is inoperable.

In certain exemplary, nonlimiting embodiments, the first detent recessof the first groove or slot is associated with the engaged or lockedposition and the second detent recess of the first groove or slot isassociated with the partially engaged or inoperably locked position.

In certain exemplary, nonlimiting embodiments, the second groove or slotdefines an elongate, substantially linear first groove or slot.

In certain exemplary, nonlimiting embodiments, the second groove or slotdefines a substantially arcuate, second groove or slot.

In certain exemplary, nonlimiting embodiments, the second groove or slotlimits the longitudinal movement of the takedown pin, relative to alower receiver.

In certain exemplary, nonlimiting embodiments, the second groove or slotlimits the rotational movement of the takedown pin to 90°, relative to alower receiver.

In certain exemplary, nonlimiting embodiments, when the takedown pin isappropriately positioned within a lower receiver of a firearm, a detentpin positioned at least partially within the second groove or slotinteracts with the second groove or slot so that the takedown pin can berepeatedly urged between an engaged or locked position, wherein thefirearm is operable, and a disengaged or unlocked position, wherein thefirearm is inoperable.

In certain exemplary, nonlimiting embodiments, the first detent recessof the second groove or slot is associated with the engaged or lockedposition and the second detent recess of the second groove or slot isassociated with the disengaged or unlocked position.

In certain exemplary, nonlimiting embodiments, the first end of thefirst groove or slot is positioned approximately 180° around the shankfrom the first end of the second groove or slot.

In certain exemplary, nonlimiting embodiments, the connecting groove orslot is formed so that the takedown pin can be rotated such that adetent pin can engage at least a portion of the connecting groove orslot to transition between the first groove or slot and the secondgroove or slot.

In certain exemplary, nonlimiting embodiments, the projection includesan arcuate or semicircular surface portion.

In certain exemplary, nonlimiting embodiments, the projection comprisesa pin that extends from the terminal surface of the shank.

In various exemplary, nonlimiting embodiments, the takedown pin of thepresent disclosure comprises a head; a shank, wherein the shank extendsfrom the head to a terminal surface; a projection extending from atleast a portion of the terminal surface; a first groove or slot formedin at least a portion of the shank; a second groove or slot formed in atleast a portion of the shank, wherein the first end of the first grooveor slot is positioned at a spaced apart location from the first end ofthe second groove or slot; and a connecting groove or slot formedbetween the first end of the first groove or slot and the first end ofthe second groove or slot.

In various exemplary, nonlimiting embodiments, the takedown pin of thepresent disclosure comprises a head; a shank, wherein said shankextends, along a longitudinal axis, from said head to a terminalsurface; a projection extending from at least a portion of said terminalsurface; a first groove or slot formed in at least a portion of saidshank, wherein a first detent recess is formed proximate a first end ofsaid first groove or slot, and wherein a second detent recess is formedproximate a second end of said first groove or slot; a second groove orslot formed in at least a portion of said shank, wherein a first detentrecess is formed proximate a first end of said second groove or slot,wherein a second detent recess is formed proximate a second end of saidsecond groove or slot, wherein said second end of said second groove orslot extends to an open or at least partially open end that extendsthrough said terminal surface of said shank and through at least aportion of said projection, and wherein said first end of said firstgroove or slot is positioned at a spaced apart location from said firstend of said second groove or slot; and a connecting groove or slotformed between said first end of said first groove or slot and saidfirst end of said second groove or slot.

In various exemplary, nonlimiting embodiments, the takedown pin of thepresent disclosure comprises a head; a shank, wherein said shank extendsfrom said head to a terminal surface; a first groove or slot formed inat least a portion of said shank, wherein a first detent recess isformed proximate a first end of said first groove or slot, wherein asecond detent recess is formed proximate a second end of said firstgroove or slot, and wherein said second end of said first groove or slotextends to an open or at least partially open end that extends throughsaid terminal surface of said shank; a second groove or slot formed inat least a portion of said shank, wherein a first detent recess isformed proximate a first end of said second groove or slot, wherein asecond detent recess is formed proximate a second end of said secondgroove or slot, and wherein said first end of said first groove or slotis positioned at a spaced apart location from said first end of saidsecond groove or slot; and a connecting groove or slot formed betweensaid first end of said first groove or slot and said first end of saidsecond groove or slot.

In various exemplary, nonlimiting embodiments, the takedown pin of thepresent disclosure comprises a head; a shank, wherein said shank extendsfrom said head to a terminal surface; a projection extending from atleast a portion of said terminal surface; a first groove or slot formedin at least a portion of said shank, wherein a first detent recess isformed proximate a first end of said first groove or slot, wherein asecond detent recess is formed proximate a second end of said firstgroove or slot; and a second groove or slot formed in at least a portionof said shank, wherein said first end of said first groove or slot ispositioned at a spaced apart location from said first end of said secondgroove or slot.

Accordingly, the present disclosure separately and optionally provides atakedown pin for a firearm that provides not only slidable engagementbetween an engaged or locked position and a disengaged or unlockedposition, but also slidable engagement between an engaged or lockedposition and a partially engaged or inoperably locked position.

The present disclosure separately and optionally provides a takedown pinfor a firearm that allows an upper receiver and a lower receiver of afirearm to be only partially rotated relative to one another.

The present disclosure separately and optionally provides a takedown pinfor a firearm that can be easily retrofitted to a firearm.

These and other aspects, features, and advantages of the presentdisclosure are described in or are apparent from the following detaileddescription of the exemplary, non-limiting embodiments of the presentdisclosure and the accompanying figures. Other aspects and features ofembodiments of the present disclosure will become apparent to those ofordinary skill in the art upon reviewing the following description ofspecific, exemplary embodiments of the present disclosure in concertwith the figures. While features of the present disclosure may bediscussed relative to certain embodiments and figures, all embodimentsof the present disclosure can include one or more of the featuresdiscussed herein. Further, while one or more embodiments may bediscussed as having certain advantageous features, one or more of suchfeatures may also be used with the various embodiments of the disclosurediscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments, it is to beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods of the present disclosure.

Any benefits, advantages, or solutions to problems that are describedherein with regard to specific embodiments are not intended to beconstrued as a critical, required, or essential feature(s) or element(s)of the present disclosure or the claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

As required, detailed exemplary embodiments of the present disclosureare discussed herein; however, it is to be understood that the disclosedembodiments are merely exemplary of the disclosure that may be embodiedin various and alternative forms, within the scope of the presentdisclosure. The figures are not necessarily to scale; some features maybe exaggerated or minimized to illustrate details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as abasis for the claims and as a representative basis for teaching oneskilled in the art to employ the present disclosure.

The exemplary embodiments of the present disclosure will be described indetail, with reference to the following figures, wherein like referencenumerals refer to like parts throughout the several views, and wherein:

FIG. 1 illustrates a perspective view of certain components of an AR-15style upper and lower receiver;

FIG. 2A illustrates a front view of a known firearm pivot pin;

FIG. 2B illustrates a left side view of a known firearm pivot pin;

FIG. 3A illustrates a front view of a known firearm take-down pin;

FIG. 3B illustrates a left side view of a known firearm take-down pin;

FIG. 4 illustrates a top view of a known take down pin and pivot pinpositioned within a lower receiver;

FIG. 5 illustrates a more detailed view of a known magazine releasebutton for an AR-15 style firearm;

FIG. 6 illustrates a more detailed, exploded view of the components ofthe known magazine release and magazine release button;

FIG. 7 illustrates a more detailed, assembled view of the components ofthe known magazine release and magazine release button;

FIG. 8 illustrates a side view showing certain exemplary components ofan AR-15 style firearm, wherein the upper receiver and the lowerreceiver are in an engaged or locked position;

FIG. 9 illustrates a side view showing certain exemplary components ofan AR-15 style firearm, wherein the upper receiver and the lowerreceiver are in a disengaged or unlocked position;

FIG. 10A illustrates an upper, front perspective view of an exemplaryembodiment of a takedown pin, according to the present disclosure;

FIG. 10B illustrates an upper, front perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 10C illustrates an upper, front perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 10D illustrates an upper, front perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 10E illustrates an upper, front perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 10F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin, according to the present disclosure;

FIG. 10G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 10H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 10I illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 11A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 11B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 11C illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 11D illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 11E illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 11F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 11G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 11H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 12 illustrates a rear, cross-sectional view of an exemplaryembodiment of a takedown pin, taken along line 12-12 of FIG. 11E,according to the present disclosure;

FIG. 13 illustrates a rear, cross-sectional view of an exemplaryembodiment of a takedown pin, taken along line 13-13 of FIG. 11E,according to the present disclosure;

FIG. 14 illustrates a rear, cross-sectional view of an exemplaryembodiment of a takedown pin, taken along line 14-14 of FIG. 11E,according to the present disclosure;

FIG. 15 illustrates a rear, cross-sectional view of an exemplaryembodiment of a takedown pin, taken along line 15-15 of FIG. 11E,according to the present disclosure;

FIG. 16 illustrates a top, cross-sectional view of an exemplary upperreceiver and an exemplary embodiment of a takedown pin, wherein thetakedown pin is in an engaged or locked position (with the detent pin inthe first groove or slot), according to the present disclosure;

FIG. 17 illustrates a top, cross-sectional view of an exemplary upperreceiver and an exemplary embodiment of a takedown pin, wherein thetakedown pin is in a partially engaged or inoperably locked position,according to the present disclosure;

FIG. 18 illustrates a top, cross-sectional view of an exemplary upperreceiver and a non-cross-sectional view of an exemplary embodiment of atakedown pin, wherein the takedown pin is in a partially engaged orinoperably locked position, according to the present disclosure;

FIG. 19 illustrates a left, side, cross-sectional view of an exemplaryupper receiver and an exemplary embodiment of a takedown pin, whereinthe takedown pin is in a partially engaged or inoperably lockedposition, according to the present disclosure;

FIG. 20 illustrates a top, cross-sectional view of an exemplary upperreceiver and a non-cross-sectional view of an exemplary embodiment of atakedown pin, wherein the takedown pin is in an engaged or lockedposition (with the detent pin in the second groove or slot), accordingto the present disclosure;

FIG. 21 illustrates a top, cross-sectional view of an exemplary upperreceiver and an exemplary embodiment of a takedown pin, wherein thetakedown pin is in a partially rotated position, according to thepresent disclosure;

FIG. 22 illustrates a top, cross-sectional view of an exemplary upperreceiver and an exemplary embodiment of a takedown pin, wherein thetakedown pin is in a disengaged or unlocked position, according to thepresent disclosure;

FIG. 23A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 23B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 24A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure; and

FIG. 24B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure

FIG. 24C illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 25A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure; and

FIG. 25B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure

FIG. 25C illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 26A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure; and

FIG. 26B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure

FIG. 26C illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 27A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure; and

FIG. 27B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure

FIG. 27C illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 28A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure; and

FIG. 28B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure

FIG. 28C illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 29A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 29B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 29C illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 29D illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 29E illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 29F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 29G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 29H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 30A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 30B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 30C illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 30D illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 30E illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 30F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 30G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 30H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 31A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 31B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 31C illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 31D illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 31E illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 31F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 31G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 31H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 32A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 32B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 32C illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 32D illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 32E illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 32F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 32G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 32H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 33A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure; and

FIG. 33B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure

FIG. 33C illustrates a rear view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 34A illustrates a side view of an exemplary embodiment of atakedown pin, according to the present disclosure;

FIG. 34B illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 34C illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 34D illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 34E illustrates a side view of an exemplary embodiment of atakedown pin in a rotated position, according to the present disclosure;

FIG. 34F illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure;

FIG. 34G illustrates an upper, rear perspective view of an exemplaryembodiment of a takedown pin in a rotated position, according to thepresent disclosure; and

FIG. 34H illustrates a front view of an exemplary embodiment of atakedown pin, according to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

For simplicity and clarification, the design factors and operatingprinciples of the takedown pin according to the present disclosure areexplained with reference to various exemplary embodiments of a takedownpin according to the present disclosure. The basic explanation of thedesign factors and operating principles of the takedown pin isapplicable for the understanding, design, and operation of the takedownpin of the present disclosure. It should be appreciated that thetakedown pin can be adapted to many applications where a takedown pincan be used.

As used herein, the word “may” is meant to convey a permissive sense(i.e., meaning “having the potential to”), rather than a mandatory sense(i.e., meaning “must”). Unless stated otherwise, terms such as “first”and “second” are used to arbitrarily distinguish between the elementssuch terms describe. Thus, these terms are not necessarily intended toindicate temporal or other prioritization of such elements.

The term “coupled”, as used herein, is defined as connected, althoughnot necessarily directly, and not necessarily mechanically. The terms“a” and “an” are defined as one or more unless stated otherwise.

Throughout this application, the terms “comprise” (and any form ofcomprise, such as “comprises” and “comprising”), “have” (and any form ofhave, such as “has” and “having”), “include”, (and any form of include,such as “includes” and “including”) and “contain” (and any form ofcontain, such as “contains” and “containing”) are used as open-endedlinking verbs. It will be understood that these terms are meant to implythe inclusion of a stated element, integer, step, or group of elements,integers, or steps, but not the exclusion of any other element, integer,step, or group of elements, integers, or steps. As a result, a system,method, or apparatus that “comprises”, “has”, “includes”, or “contains”one or more elements possesses those one or more elements but is notlimited to possessing only those one or more elements. Similarly, amethod or process that “comprises”, “has”, “includes” or “contains” oneor more operations possesses those one or more operations but is notlimited to possessing only those one or more operations.

It should also be appreciated that the terms “takedown pin”, “upperreceiver”, “lower receiver”, and “firearm” are used for basicexplanation and understanding of the operation of the systems, methods,and apparatuses of the present disclosure. Therefore, the terms“takedown pin”, “upper receiver”, “lower receiver”, and “firearm” arenot to be construed as limiting the systems, methods, and apparatuses ofthe present disclosure.

For simplicity and clarification, the takedown pin of the presentdisclosure will be described as being used in conjunction with afirearm, such as an AR-15 or M4 style rifle or carbine. However, itshould be appreciated that these are merely exemplary embodiments of thetakedown pin and are not to be construed as limiting the presentdisclosure. Thus, the takedown pin of the present disclosure may beutilized in conjunction with any appropriate firearm, object, or device.

Turning now to the drawing Figs., as discussed above, FIGS. 1-9illustrate certain elements and/or aspects of a known AR-15 or M4 stylerifle or carbine.

FIGS. 10-22 illustrate certain elements and/or aspects of an exemplaryembodiment of the takedown pin 300, according to the present disclosure.In illustrative, non-limiting embodiment(s) of the present disclosure,as illustrated in FIGS. 16-22, the exemplary embodiments of the takedownpin 300 are utilized in conjunction with an upper receiver 10, a lowerreceiver 20, and/or firearm 30. As illustrated, the upper receiver 10,lower receiver 20, and/or firearm 30 most closely resemble an AR-15 orM4 style platform. However, it should be understood and appreciated thatthe upper receiver 10, lower receiver 20, and/or firearm 30 are not solimited and the takedown pin 300 of the present disclosure can beutilized in connection with any AR-15 or M4 style platform or any otherfirearm or platform, such as, for example, a FAL or SCAR style firearm,or any other firearm or platform having a pivotably or hingedlyconnected upper and lower element or component.

With that understanding, the firearm 30, as illustrated in FIGS. 16-22,comprises an upper receiver 10 and a lower receiver 20. The upperreceiver 10 and the lower receiver 20 comprise at least some of an upperpivot pin lug aperture 12, an upper takedown lug aperture 18, lowerpivot pin lug apertures 22, lower takedown lug apertures 28, a pivot pin100, a takedown pin 200, a magazine release button 50 that travels backand forth within at least a portion of a magazine release buttonreceiving cavity. The magazine release button 50 includes at least someof an internal aperture 52, a magazine release spring 59, a magazinerelease 55, a magazine release connection shaft 56, a threaded portion57, and a magazine engagement projection 58.

It should be appreciated that each of these elements (as well as other,similarly named elements of the upper receiver 10 and the lower receiver20) correspond to and operate similarly to similarly named elements, asdescribed herein with reference to the elements of the upper receiver 10and a lower receiver 20 of FIGS. 1-9. Thus, it should be appreciatedthat the upper receiver 10 and the lower receiver 20 may incorporate oneor any of the features or elements of the upper receiver 10 and a lowerreceiver 20 of FIGS. 1-9.

FIGS. 10A-22 illustrate an exemplary embodiment of a takedown pin 300.In various exemplary, nonlimiting embodiments, the takedown pin 300comprises a head 310 and a shank 330. In various exemplary embodiments,the shank 330 comprises an elongate, cylindrical shank portion thatextends from the head 310 to a terminal surface 334. In someembodiments, an intermediate portion 320, having a reduced diameter whencompared to a diameter of the shank 330, is formed or disposed betweenthe shank 330 and the head 310.

The head 310 extends from the shank 330 or the intermediate portion 320and is generally formed so as to allow a user to grasp and slide orrotate the takedown pin 300. In various exemplary embodiments, at leasta portion of the head 310 is textured to provide greater purchase on atleast a portion of the head 310 of the takedown pin 300. At least aportion of the head 310 may be textured using, for example, stippling,knurling, checkering, annular rings, or other patterns. Providingtexture to a portion of the head 310 can aid in transitioning thetakedown pin 300 between an engaged or locked position, a partiallyengaged or inoperably locked position, and/or a disengaged or unlockedposition.

In various exemplary, nonlimiting embodiments, the overall length of theshank 330, along its longitudinal axis, A_(L), from the head 310 to theterminal surface 334, is similar to the overall length of the shank of aknown takedown pin 10. Similarly, an outer diameter of at least aportion of the shank 330 is similar to the overall outer diameter of theshank of a known takedown pin 10.

Thus, the shank 330 of the takedown pin 300 is formed so as to beappropriately inserted within and be repeatably slidable within theupper takedown pin aperture 18 of an upper receiver 10 and the lowertakedown pin apertures 28 of a lower receiver 20. Thus. It should beappreciated that the length and the overall outer diameter of the shank330 are designed choices based upon the firearm or other device withwhich the takedown pin 300 is to be utilized.

A projection 335 extends from at least a portion of the terminal surface334 of the takedown pin 300.

A first groove or slot 340 is formed in the shank 330. In variousexemplary, nonlimiting embodiments, the first groove or slot 340 definesa continuous, elongate, linear first groove or slot 340. The firstgroove or slot 340 extends, within the shank 330, along the longitudinalaxis A_(L) of the takedown pin 300.

The first groove or slot 340 can be used to limit the rotationalmovement (range of rotation) and the longitudinal movement (movementalong the longitudinal axis, A_(L)) of the takedown pin 300, relative tothe lower receiver 20. In various exemplary embodiments, the firstgroove or slot 340 comprises a linear slot, which can be used to limitthe rotational movement (range of rotation) of the takedown pin 300 to0°. Thus, when the takedown pin 300 is appropriately positioned within alower receiver 20, the detent pin 41 is positioned at least partiallywithin the first groove or slot 340. The detent pin 41 interacts withthe first groove or slot 340, so that the takedown pin 300 can berepeatedly urged (along the longitudinal axis, A_(L)) between theengaged or locked position, as illustrated in FIG. 16, and the partiallyengaged or inoperably locked position, as illustrated in FIGS. 17-19.

A first detent recess 342 is formed proximate a first end of the firstgroove or slot 340 and a second detent recess 347 is formed proximate asecond end of the first groove or slot 340. The first detent recess 342is associated with the engaged or locked position and the second detentrecess 347 is associated with the partially engaged or inoperably lockedposition.

While interaction between the first groove or slot 340 and the detentpin 41 can be used to define or limit the range of rotation andlongitudinal movement of the takedown pin 300, the first detent recess342 and the second detent recess 347 are formed so as to be engaged bythe detent pin 41 at the engaged or locked position, as illustrated inFIG. 16 and at the partially engaged or inoperably locked position, asillustrated in FIGS. 17-19. A detent spring 47 provides a spring biasingforce that urges the detent pin 41 into the first groove or slot 340.Thus, once the detent pin 41 engages the first groove or slot 340, thetakedown pin 300 is slidably movable between engaged or locked positionand the partially engaged or inoperably locked position, but additionalfrictional engagement is provided between the detent pin 41 and thefirst detent recess 342 and the second detent recess 347 to furthersecure the takedown pin 300 in either the engaged or locked position orthe partially engaged or inoperably locked position. Thus, the firstdetent recess 342 and the second detent recess 347 act as mechanicalstops, within or proximate terminating positions of the first groove orslot 340, to limit the movement of the takedown pin 300.

A second groove or slot 350 is also formed in the shank 330. In variousexemplary, nonlimiting embodiments, the second groove or slot 350defines a continuous, curved, recurved, arcuate, or partially arcuatesecond groove or slot 350. A first detent recess 352 is formed proximatea first end of the second groove or slot 350 and a second detent recess357 is formed proximate a second end of the second groove or slot 350.The second groove or slot 350 can be used to limit the rotationalmovement (range of rotation) and the longitudinal movement (movementalong the longitudinal axis, A_(L)) of the takedown pin 300, relative tothe lower receiver 20.

The second groove or slot 350 is formed so as to allow the takedown pin300 to traverse or pass through a desired range of rotation, as thetakedown pin 300 is rotated or manipulated to slide within at least oneof the lower takedown pin apertures 28 of a lower receiver 20, relativeto the takedown pin detent pin 41 of the lower receiver 20. The degreeof curve or arc of the second groove or slot 350 is based on the desiredrange of rotation of the takedown pin 300 over the length of the shank330 or the second groove or slot 350. For example, as illustrated, ifthe takedown pin 300 is configured to travel over a range of 90° ofrotation from the engaged or locked position to the disengaged orunlocked position, the second groove or slot 350 is configured to allowthe takedown pin 300 to rotate 90°.

It should be appreciated that the desired range of rotation of thetakedown pin 300 is a design choice based upon the amount of rotationdesired to effect the transition of the takedown pin 300 from theengaged or locked position, as illustrated in FIG. 20, to the disengagedor unlocked position, as illustrated in FIG. 22. Thus, in variousexemplary embodiments, as illustrated most clearly in FIG. 15, thedesired range of rotation, Θ2, is 90°. In certain other exemplaryembodiments, the desired degree of rotation may optionally be between 0°and 90°. In still other exemplary embodiments, the desired degree ofrotation may optionally be greater than 90°.

Thus, when the takedown pin 300 is appropriately positioned within alower receiver 20, the detent pin 41 is positioned at least partiallywithin the second groove or slot 350. When the detent pin 41 ispositioned at least partially within the second groove or slot 350, thedetent pin 41 interacts with the second groove or slot 350, so that thetakedown pin 300 can be rotatedly transitioned between the engaged orlocked position, as illustrated in FIG. 20 and the disengaged orunlocked position, as illustrated in FIG. 22.

FIG. 21 illustrates an intermediate position, as the takedown pin 300 isrotatably transitioned between the engaged or locked position and thedisengaged or unlocked position.

While interaction between the second groove or slot 350 and the detentpin 41 can be used to define or limit the range of rotation andlongitudinal movement of the takedown pin 300, the first detent recess352 and the second detent recess 357 are formed so as to be engaged bythe detent pin 41 at the engaged or locked position, as illustrated inFIG. 20 and at the disengaged or unlocked position, as illustrated inFIG. 22. They detent spring 47 provides a spring biasing force thaturges the detent pin 41 into the second groove or slot 350. Thus, oncethe detent pin 41 engages the second groove or slot 350, the takedownpin 300 is slidably rotatable between engaged or locked position and thedisengaged an unlocked position, but additional frictional engagement isprovided between the detent pin 41 and the first detent recess 352 andthe second detent recess 357 to further secure the takedown pin 300 ineither the engaged or locked position or the disengaged or unlockedposition. Thus, the first detent recess 352 and the second detent recess357 act as mechanical stops, within or proximate terminating positionsof the second groove or slot 350, to limit the movement of the takedownpin 300.

In certain exemplary, nonlimiting embodiments, the first detent recess342 and the first detent recess 352 are the same recess and both thefirst groove or slot 340 and the second groove or slot 350 extend fromthe same first detent recess.

In certain exemplary, nonlimiting embodiments, the first detent recess342 (and the first end of the first groove or slot 340) is positioned ata spaced apart location from the second detent recess 352 (and the firstend of the second groove or slot 350). For example, as illustrated, thefirst detent recess 342 (and the first end of the first groove or slot340) is positioned 180° (as illustrated by Θ1 in FIGS. 12 and 15) aroundthe shank 330 from the second detent recess 352 (and the first end ofthe second groove or slot 350). In these exemplary embodiments, aconnecting groove or slot 360 is formed between the first end of thefirst groove or slot 340 and the first end of the second groove or slot350. The connecting groove or slot 360 is formed so that the takedownpin 300 can be rotated such that the detent pin 41 engages at least aportion of the connecting groove or slot 360 to transition between thefirst end of the first groove or slot 340 and the first end of thesecond groove or slot 350.

The first detent recess 342 is formed proximate a first end of theconnecting groove or slot 360 and the first detent recess 352 is formedproximate a second end of the connecting groove or slot 360.

As illustrated most clearly in FIGS. 16-22, the upper receiver 10 andthe lower receiver 20 are pivotably attached or coupled, via the pivotpin. When the upper receiver 10 and the lower receiver 20 are attachedor coupled in an operable configuration, the upper takedown pin lugaperture 18 is aligned between the lower takedown pin lug apertures 28.When the upper takedown pin lug aperture 18 is not aligned between thelower takedown pin lug apertures 28, the upper receiver 10 and the lowerreceiver 20 may still be attached or coupled, via the pivot pin, but arenot in an operable configuration.

When the takedown pin 300 is appropriately positioned within the lowertakedown pin lug aperture(s) 28 of the lower receiver 20, the detent pin41 may be positioned at least partially within the first groove or slot340. When the detent pin 41 is positioned at least partially within thefirst groove or slot 340, the detent pin 41 interacts with the firstgroove or slot 340, so that the takedown pin 300 can be repeatedly urged(along the longitudinal axis, A_(L)) between the engaged or lockedposition, as illustrated in FIG. 16, and the partially engaged orinoperably locked position, as illustrated in FIGS. 17-19.

When the takedown pin 300 is in the engaged or locked position(typically with the detent pin 41 at least partially seated within thesecond detent recess 347), at least a portion of the takedown pin 300maintains the upper takedown pin lug aperture 18 in locked alignmentbetween the lower takedown pin lug apertures 28, thus maintaining theupper receiver 10 and the lower receiver 20 in an operableconfiguration.

If the takedown pin 300 is urged, along its longitudinal axis, A_(L), tothe partially engaged or inoperably locked position (typically with thedetent pin 41 at least partially seated within the first detent recess342), the shank 330 is withdrawn a sufficient distance to from the uppertakedown pin lug aperture 18 that the terminal surface 334 is withdrawnfrom the upper takedown pin lug aperture 18. However, in the partiallyengaged or inoperably locked position, at least a portion of theprojection 335 extends into the upper takedown pin lug aperture 18. Bymaintaining at least a portion of the projection 335 in the uppertakedown pin lug aperture 18, the upper receiver 10 is able to bepivoted, via the pivot pin, to an inoperable position, relative to thelower receiver 20. Because at least a portion of the projection 335 ismaintained within at least a portion of the upper takedown pin lugaperture 18, the upper receiver 10 is not able to pivot freely, relativeto the lower receiver 20, but is only able to pivot between the engagedor locked position and the partially engaged or inoperably lockedposition.

In various exemplary embodiments, the projection 335 includes an arcuateor semicircular surface, which corresponds to a portion of the articleor curve of the upper takedown pin lug aperture 18. However, in certainexemplary embodiments, the projection 335 includes an alternativesurface or profile. In still other exemplary embodiments, the projection335 comprises a pin or other protrusion that extends from the terminalsurface 334 of the shank 330. The projection 335 only extends from asufficient portion of the terminal surface 334 so as to interact withthe upper takedown pin lug aperture 18 to allow the upper receiver 10 topivot to the partially engaged or inoperably locked position.

When the takedown pin 300 is in the engaged or locked position, thetakedown pin 300 can be rotated, via interaction between the detent pin41 and the connecting channel 360, between the first detent recess 342and the first detent recess 352. This allows the detent pin 41 to berotated between the first groove or slot 340 and the second groove orslot 350.

When the detent pin 41 is positioned at least partially within thesecond groove or slot 350, the detent pin 41 interacts with the secondgroove or slot 350, so that the takedown pin 300 can be repeatedly,rotationally urged between the engaged or locked position, asillustrated in FIG. 20, and the disengaged or unlocked position, asillustrated in FIG. 22.

When the takedown pin 300 is in the disengaged or unlocked (typicallywith the detent pin 41 at least partially seated within the seconddetent recess 357), the shank 330 and projection 335 are withdrawn asufficient distance to from the upper takedown pin lug aperture 18 thatthe terminal surface 334 and through at least a portion of theprojection 335 are withdrawn from the upper takedown pin lug aperture18. By withdrawing the shank 330 and through at least a portion of theprojection 335 from the upper takedown pin lug aperture 18, the upperreceiver 10 is able to be freely pivoted, via the pivot pin, relative tothe lower receiver 20.

FIGS. 23A-23B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 400. In various exemplary, nonlimitingembodiments, the takedown pin 400 comprises at least some of a head 410,a shank 430 extending from the head 410 to a terminal surface 434, anoptional intermediate portion 420, a projection 435, a first groove orslot 440 having an associated first detent recess 442 and second detentrecess 447, a second groove or slot 450 having an associated firstdetent recess 452 and second detent recess 457, and a connecting grooveor slot 460.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 310, the shank330 extending from the head 310 to the terminal surface 334, theoptional intermediate portion 320, the projection 335, the first grooveor slot 340 having the associated first detent recess 342 and seconddetent recess 347, the second groove or slot 350 having the associatedfirst detent recess 352 and second detent recess 357, and the connectinggroove or slot 360, as described herein.

However, as illustrated in FIGS. 23A-23B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the second grooveor slot 450 is not curved or arcuate, but is linear or substantiallylinear. Thus, when a detent pin 41 is positioned within the secondgroove or slot 450, a rotational force is not necessary to manipulatethe takedown pin 400 between the engaged or locked position and thedisengaged or unlocked position.

FIGS. 24A-24B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 500. In various exemplary, nonlimitingembodiments, the takedown pin 500 comprises at least some of a head 510,a shank 530 extending from the head 510 to a terminal surface 534, anoptional intermediate portion 520, a projection 535, a first groove orslot 540 having an associated first detent recess 542 and second detentrecess 547, a second groove or slot 550 having an associated firstdetent recess 552 and second detent recess 557, and a connecting grooveor slot 560.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 410, the shank430 extending from the head 410 to the terminal surface 434, theoptional intermediate portion 420, the projection 435, the first grooveor slot 440 having the associated first detent recess 442 and seconddetent recess 447, the second groove or slot 450 having the associatedfirst detent recess 452 and second detent recess 457, and the connectinggroove or slot 460, as described herein.

However, as illustrated in FIGS. 24A-24B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the second grooveor slot 550 is not closed or bounded on both ends. Instead, the secondgroove or slot 550 extends to an open or at least partially open end553. The open or at least partially open end 553 extends through theterminal surface 534 of the shank 530 and through at least a portion ofthe projection 535.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 553 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 500 or extend away from the outer surface of the takedownpin 500, as the open or at least partially open end 553 extends towardthe terminal surface 534 of the shank 530.

By extending the second groove or slot 550 to an open or at leastpartially open end 553, the takedown pin 500 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 500, the open or atleast partially open end 553 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the secondgroove or slot 550, through the open or at least partially open end 553.Then, as the shank 530 is further urged into the lower receiver 20, aportion of the detent pin 41 is maintained within the second groove orslot 550.

In various exemplary embodiments, as described herein, the open or atleast partially open end 553 extends through the terminal surface 534 ofthe shank 530 and through at least a portion of the projection 535. Inthese exemplary embodiments, the projection 535 can be utilized toassist in orienting the detent pin 41 within the second groove or slot550 and initially overcoming the spring bias that the detent pin spring47 provides to the detent pin 41.

During potential removal of the takedown pin 500, a sufficientwithdrawing force can be applied to the takedown pin 500, such that thedetent pin 41 is removed from the second detent recess 557 (if included)sufficient to allow at least a portion of the detent pin 41 to travel tothe open or at least partially open end 553 and be removed from thesecond groove or slot 550 and the takedown pin 500.

In this manner, the takedown pin 500 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

FIGS. 25A-25B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 600. In various exemplary, nonlimitingembodiments, the takedown pin 600 comprises at least some of a head 610,a shank 630 extending from the head 610 to a terminal surface 634, anoptional intermediate portion 620, a projection 635, a first groove orslot 640 having an associated first detent recess 642 and second detentrecess 647, a second groove or slot 650 having an associated firstdetent recess 652 and second detent recess 657, and a connecting grooveor slot 660.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 510, the shank530 extending from the head 510 to the terminal surface 534, theoptional intermediate portion 520, the projection 535, the first grooveor slot 540 having the associated first detent recess 542 and seconddetent recess 547, the second groove or slot 550 having the associatedfirst detent recess 552 and second detent recess 557, and the connectinggroove or slot 560, as described herein.

However, as illustrated in FIGS. 25A-25B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the first grooveor slot 640 is not closed or bounded on both ends. Instead, the firstgroove or slot 640 extends to an open or at least partially open end643. The open or at least partially open end 643 extends through theterminal surface 634 of the shank 630.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 643 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 600 or extend away from the outer surface of the takedownpin 600, as the open or at least partially open end 643 extends towardthe terminal surface 634 of the shank 630.

By extending the first groove or slot 640 to an open or at leastpartially open end 643, the takedown pin 600 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 600, the open or atleast partially open end 653 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the firstgroove or slot 640, through the open or at least partially open end 643.Then, as the shank 630 is further urged into the lower receiver 20, aportion of the detent pin 41 is maintained within the first groove orslot 640.

During potential removal of the takedown pin 600, a sufficientwithdrawing force can be applied to the takedown pin 600, such that thedetent pin 41 is removed from the second detent recess 657 (if included)sufficient to allow at least a portion of the detent pin 41 to travel tothe open or at least partially open end 643 and be removed from thefirst groove or slot 640 and the takedown pin 600.

In this manner, the takedown pin 600 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

FIGS. 26A-26B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 700. In various exemplary, nonlimitingembodiments, the takedown pin 700 comprises at least some of a head 710,a shank 730 extending from the head 710 to a terminal surface 734, anoptional intermediate portion 720, a projection 735, a first groove orslot 740 having an associated first detent recess 742 and second detentrecess 747, and a second groove or slot 750 having an associated firstdetent recess 752 and second detent recess 757.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 510, the shank530 extending from the head 510 to the terminal surface 534, theoptional intermediate portion 520, the projection 535, the first grooveor slot 540 having the associated first detent recess 542 and seconddetent recess 547, and the second groove or slot 550 having theassociated first detent recess 552 and second detent recess 557, asdescribed herein.

However, as illustrated in FIGS. 26A-26B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the connectinggroove or slot 560 is removed and the first groove or slot 740 isseparate and discrete from the second groove or slot 750.

By providing a first groove or slot 740 that is separate and discretefrom a second groove or slot 750, discrete, desired features of thetakedown pin 700 can be utilized, based upon the manner in which thetakedown pin 700 is installed in the lower receiver 20. For example, thetakedown pin 700 may optionally be installed such that a portion of thedetent pin 41 is positioned within the first groove or slot 740.Alternatively, the takedown pin 700 may optionally be installed suchthat a portion of the detent pin 41 is positioned within the secondgroove or slot 750.

If the takedown pin 700 is installed such that a portion of the detentpin 41 is positioned within the first groove or slot 740, the takedownpin 700 may only be manipulated between an engaged or locked positionand a partially engaged or operably locked position. For example, if thetakedown pin 700 is urged from an engaged or locked position (whereinthe upper receiver 10 and the lower receiver 20 are maintained in anoperable configuration) to a partially engaged or inoperably lockedposition, the shank 730 is withdrawn a sufficient distance to from theupper takedown pin lug aperture 18 that the terminal surface 734 iswithdrawn from the upper takedown pin lug aperture 18. However, in thepartially engaged or inoperably locked position, at least a portion ofthe projection 735 extends into the upper takedown pin lug aperture 18.By maintaining at least a portion of the projection 735 in the uppertakedown pin lug aperture 18, the upper receiver 10 is able to bepivoted, via the pivot pin, to an inoperable position, relative to thelower receiver 20. Because at least a portion of the projection 735 ismaintained within at least a portion of the upper takedown pin lugaperture 18, the upper receiver 10 is not able to pivot freely, relativeto the lower receiver 20, but is only able to pivot between the engagedor locked position and the partially engaged or inoperably lockedposition.

If the takedown pin 700 is installed such that a portion of the detentpin 41 is positioned within the second groove or slot 750, the takedownpin 700 may only be manipulated between an engaged or locked positionand a disengaged or unlocked position. For example, if the takedown pin700 is urged from an engaged or locked position (wherein the upperreceiver 10 and the lower receiver 20 are maintained in an operableconfiguration) to a disengaged or unlocked position, the detent pin 41interacts with the second groove or slot 750 such that the shank 730 andprojection 735 are withdrawn a (if included) sufficient distance to fromthe upper takedown pin lug aperture 18 that the terminal surface 734 andthrough at least a portion of the projection 735 are withdrawn from theupper takedown pin lug aperture 18. By withdrawing the shank 730 andthrough at least a portion of the projection 735 from the upper takedownpin lug aperture 18, the upper receiver 10 is able to be freely pivoted,via the pivot pin, relative to the lower receiver 20.

FIGS. 27A-27B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 800. In various exemplary, nonlimitingembodiments, the takedown pin 800 comprises at least some of a head 810,a shank 830 extending from the head 810 to a terminal surface 834, anoptional intermediate portion 820, a projection 835, a first groove orslot 840 having an associated first detent recess 842 and second detentrecess 847, and a second groove or slot 850 having an associated firstdetent recess 852 and second detent recess 857.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 710, the shank730 extending from the head 710 to the terminal surface 734, theoptional intermediate portion 720, the projection 735, the first grooveor slot 740 having the associated first detent recess 742 and seconddetent recess 747, and the second groove or slot 750 having theassociated first detent recess 752 and second detent recess 757, asdescribed herein.

However, as illustrated in FIGS. 27A-27B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the first grooveor slot 840 is not closed or bounded on both ends. Instead, the firstgroove or slot 840 extends to an open or at least partially open end843. The open or at least partially open end 843 extends through theterminal surface 834 of the shank 830.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 843 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 800 or extend away from the outer surface of the takedownpin 800, as the open or at least partially open end 843 extends towardthe terminal surface 834 of the shank 830.

By extending the first groove or slot 840 to an open or at leastpartially open end 843, the takedown pin 800 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 800, the open or atleast partially open end 843 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the firstgroove or slot 840, through the open or at least partially open end 843.Then, as the shank 830 is further urged into the lower receiver 20, aportion of the detent pin 41 is maintained within the first groove orslot 840.

During potential removal of the takedown pin 800, a (if included)sufficient withdrawing force can be applied to the takedown pin 800,such that the detent pin 41 is removed from the second detent recess 847(if included) sufficient to allow at least a portion of the detent pin41 to travel to the open or at least partially open end 843 and beremoved from the first groove or slot 840 and the takedown pin 800.

In this manner, the takedown pin 800 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

Thus, if the takedown pin 800 is installed such that a portion of thedetent pin 41 is positioned within the first groove or slot 840, thetakedown pin 800 may be manipulated between an engaged or lockedposition (with the detent pin 41 positioned within or proximate thefirst detent recess 842), a partially engaged or operably lockedposition (with the detent pin 41 positioned within or proximate thesecond detent recess 847), or a removed position, where in the detentpin 41 is urged past the second detent recess 847, through the open orat least partially open end 843.

FIGS. 28A-28B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 900. In various exemplary, nonlimitingembodiments, the takedown pin 900 comprises at least some of a head 910,a shank 930 extending from the head 910 to a terminal surface 934, anoptional intermediate portion 920, a projection 935, a first groove orslot 940 having an associated first detent recess 942 and second detentrecess 947, and a second groove or slot 950 having an associated firstdetent recess 952 and second detent recess 957.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 710, the shank730 extending from the head 710 to the terminal surface 734, theoptional intermediate portion 720, the projection 735, the first grooveor slot 740 having the associated first detent recess 742 and seconddetent recess 747, and the second groove or slot 750 having theassociated first detent recess 752 and second detent recess 757, asdescribed herein.

However, as illustrated in FIGS. 28A-28B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the second grooveor slot 950 is not closed or bounded on both ends. Instead, the secondgroove or slot 950 extends to an open or at least partially open end953. The open or at least partially open end 953 extends through theterminal surface 934 of the shank 930 and through at least a portion ofthe projection 935.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 953 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 900 or extend away from the outer surface of the takedownpin 900, as the open or at least partially open end 953 extends towardthe terminal surface 934 of the shank 930.

By extending the second groove or slot 950 to an open or at leastpartially open end 953, the takedown pin 900 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 900, the open or atleast partially open end 953 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the secondgroove or slot 950, through the open or at least partially open end 953.Then, as the shank 930 is further urged into the lower receiver 20, aportion of the detent pin 41 is maintained within the second groove orslot 950.

During potential removal of the takedown pin 900, a sufficientwithdrawing force can be applied to the takedown pin 900, such that thedetent pin 41 is removed from the second detent recess 957 (if included)sufficient to allow at least a portion of the detent pin 41 to travel tothe open or at least partially open end 953 and be removed from thesecond groove or slot 950 and the takedown pin 900.

In this manner, the takedown pin 900 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

Thus, if the takedown pin 900 is installed such that a portion of thedetent pin 41 is positioned within the second groove or slot 950, thetakedown pin 900 may be manipulated between an engaged or lockedposition, a disengaged or unlocked position, and a removal position.

FIGS. 29A-29H illustrate certain elements or components of an exemplaryembodiment of a takedown pin 1000. In various exemplary, nonlimitingembodiments, the takedown pin 1000 comprises at least some of a head1010, a shank 1030 extending from the head 1010 to a terminal surface1034, an optional intermediate portion 1020, a projection 1035, a firstgroove or slot 1040 having an associated first detent recess 1042 andsecond detent recess 1047, a second groove or slot 1050 having anassociated first detent recess 1052 and second detent recess 1057, and aconnecting groove or slot 1060.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 310, the shank330 extending from the head 310 to the terminal surface 334, theoptional intermediate portion 320, the projection 335, the first grooveor slot 340 having the associated first detent recess 342 and seconddetent recess 347, the second groove or slot 350 having the associatedfirst detent recess 352 and second detent recess 357, and the connectinggroove or slot 360, as described herein.

However, as illustrated in FIGS. 29A-29H, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the second grooveor slot 1050 is not closed or bounded on both ends. Instead, the secondgroove or slot 1050 extends to an open or at least partially open end1053. The open or at least partially open end 1053 extends through theterminal surface 1034 of the shank 1030 and through at least a portionof the projection 1035.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 1053 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 1000 or extend away from the outer surface of the takedownpin 1000, as the open or at least partially open end 1053 extends towardthe terminal surface 1034 of the shank 1030.

By extending the second groove or slot 1050 to an open or at leastpartially open end 1053, the takedown pin 1000 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 1000, the open or atleast partially open end 1053 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the secondgroove or slot 1050, through the open or at least partially open end1053. Then, as the shank 1030 is further urged into the lower receiver20, a portion of the detent pin 41 is maintained within the secondgroove or slot 1050.

During potential removal of the takedown pin 1000, a sufficientwithdrawing force can be applied to the takedown pin 1000, such that thedetent pin 41 is removed from the second detent recess 1057 (ifincluded) sufficient to allow at least a portion of the detent pin 41 totravel to the open or at least partially open end 1053 and be removedfrom the second groove or slot 1050 and the takedown pin 1000.

In this manner, the takedown pin 1000 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

FIGS. 30A-30H illustrate certain elements or components of an exemplaryembodiment of a takedown pin 1100. In various exemplary, nonlimitingembodiments, the takedown pin 1100 comprises at least some of a head1110, a shank 1130 extending from the head 1110 to a terminal surface1134, an optional intermediate portion 1120, a projection 1135, a firstgroove or slot 1140 having an associated first detent recess 1142 andsecond detent recess 1147, a connecting groove or slot 1160, and asecond groove or slot 1150 having an associated first detent recess 1152and second detent recess 1157.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 310, the shank330 extending from the head 310 to the terminal surface 334, theoptional intermediate portion 320, the projection 335, the first grooveor slot 340 having the associated first detent recess 342 and seconddetent recess 347, the connecting groove or slot 360, and the secondgroove or slot 350 having the associated first detent recess 352 andsecond detent recess 357, as described herein.

However, as illustrated in FIGS. 30A-30H, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the first grooveor slot 1140 is not closed or bounded on both ends. Instead, the firstgroove or slot 1140 extends to an open or at least partially open end1143. The open or at least partially open end 1143 extends through theterminal surface 1134 of the shank 1130.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 1143 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 1100 or extend away from the outer surface of the takedownpin 1100, as the open or at least partially open end 1143 extends towardthe terminal surface 1134 of the shank 1130.

By extending the first groove or slot 1140 to an open or at leastpartially open end 1143, the takedown pin 1100 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 1100, the open or atleast partially open end 1143 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the firstgroove or slot 1140, through the open or at least partially open end1143. Then, as the shank 1130 is further urged into the lower receiver20, a portion of the detent pin 41 is maintained within the first grooveor slot 1140.

During potential removal of the takedown pin 1100, a sufficientwithdrawing force can be applied to the takedown pin 1100, such that thedetent pin 41 is removed from the second detent recess 1157 (ifincluded) sufficient to allow at least a portion of the detent pin 41 totravel to the open or at least partially open end 1143 and be removedfrom the first groove or slot 1140 and the takedown pin 1100.

In this manner, the takedown pin 1100 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

FIGS. 31A-31H illustrate certain elements or components of an exemplaryembodiment of a takedown pin 1200. In various exemplary, nonlimitingembodiments, the takedown pin 1200 comprises at least some of a head1210, a shank 1231 extending from the head 1210 to a terminal surface1234, an optional intermediate portion 1220, a projection 1235, a firstgroove or slot 1240 having an associated first detent recess 1242 andsecond detent recess 1247, and a second groove or slot 1250 having anassociated first detent recess 1252 and second detent recess 1257.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 1010, theshank 1031 extending from the head 1010 to the terminal surface 1034,the optional intermediate portion 1020, the projection 1035, the firstgroove or slot 1040 having the associated first detent recess 1042 andsecond detent recess 1047, and the second groove or slot 1050 having theassociated first detent recess 1052 and second detent recess 1057, asdescribed herein.

However, as illustrated in FIGS. 31A-31H, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the connectinggroove or slot 1060 is removed and the first groove or slot 1240 isseparate and discrete from the second groove or slot 1250. Furthermore,the second groove or slot 1250 extends to an open or at least partiallyopen end 1253.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 1253 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 1200 or extend away from the outer surface of the takedownpin 1200, as the open or at least partially open end 1253 extends towardthe terminal surface 1234 of the shank 1230.

By extending the second groove or slot 1250 to an open or at leastpartially open end 1253, the takedown pin 1200 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 1200, the open or atleast partially open end 1253 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the secondgroove or slot 1250, through the open or at least partially open end1253. Then, as the shank 1231 is further urged into the lower receiver20, a portion of the detent pin 41 is maintained within the secondgroove or slot 1250.

During potential removal of the takedown pin 1200, a sufficientwithdrawing force can be applied to the takedown pin 1200, such that thedetent pin 41 is removed from the second detent recess 1257 (ifincluded) sufficient to allow at least a portion of the detent pin 41 totravel to the open or at least partially open end 1253 and be removedfrom the second groove or slot 1250 and the takedown pin 1200.

In this manner, the takedown pin 1200 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

FIGS. 32A-32H illustrate certain elements or components of an exemplaryembodiment of a takedown pin 1300. In various exemplary, nonlimitingembodiments, the takedown pin 1300 comprises at least some of a head1310, a shank 1332 extending from the head 1310 to a terminal surface1334, an optional intermediate portion 1320, a projection 1335, a firstgroove or slot 1340 having an associated first detent recess 1342 andsecond detent recess 1347, and a second groove or slot 1350 having anassociated first detent recess 1352 and second detent recess 1357.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 1010, theshank 1032 extending from the head 1010 to the terminal surface 1034,the optional intermediate portion 1020, the projection 1035, the firstgroove or slot 1040 having the associated first detent recess 1042 andsecond detent recess 1047, and the second groove or slot 1050 having theassociated first detent recess 1052 and second detent recess 1057, asdescribed herein.

However, as illustrated in FIGS. 32A-32H, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the connectinggroove or slot 1060 is removed and the first groove or slot 1340 isseparate and discrete from the second groove or slot 1350.

FIGS. 33A-33B illustrate certain elements or components of an exemplaryembodiment of a takedown pin 1400. In various exemplary, nonlimitingembodiments, the takedown pin 1400 comprises at least some of a head1410, a shank 1430 extending from the head 1410 to a terminal surface1434, an optional intermediate portion 1420, a first groove or slot 1440having an associated first detent recess 1442 and second detent recess1447, a second groove or slot 1450 having an associated first detentrecess 1452 and second detent recess 1457, and a connecting groove orslot 1460.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 410, the shank430 extending from the head 410 to the terminal surface 434, theoptional intermediate portion 420, the first groove or slot 440 havingthe associated first detent recess 442 and second detent recess 447, thesecond groove or slot 450 having the associated first detent recess 452and second detent recess 457, and the connecting groove or slot 460, asdescribed herein.

However, as illustrated in FIGS. 33A-33B, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the projection 435is not included and the second groove or slot 1450 is not closed orbounded on both ends. Instead, the second groove or slot 1450 extends toan open or at least partially open end 1453. The open or at leastpartially open end 1453 extends through the terminal surface 1434 of theshank 1430.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 1453 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 1400 or extend away from the outer surface of the takedownpin 1400, as the open or at least partially open end 1453 extends towardthe terminal surface 1434 of the shank 1430.

By extending the second groove or slot 1450 to an open or at leastpartially open end 1453, the takedown pin 1400 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30. Forexample, during installation of the takedown pin 1400, the open or atleast partially open end 1453 can be aligned with a detent pin 41, so asto allow a portion of the detent pin 41 to initially enter the secondgroove or slot 1450, through the open or at least partially open end1453. Then, as the shank 1430 is further urged into the lower receiver20, a portion of the detent pin 41 is maintained within the secondgroove or slot 1450.

During potential removal of the takedown pin 1400, a sufficientwithdrawing force can be applied to the takedown pin 1400, such that thedetent pin 41 is removed from the second detent recess 1457 (ifincluded) sufficient to allow at least a portion of the detent pin 41 totravel to the open or at least partially open end 1453 and be removedfrom the second groove or slot 1450 and the takedown pin 1400.

In this manner, the takedown pin 1400 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

FIGS. 34A-34H illustrate certain elements or components of an exemplaryembodiment of a takedown pin 1500. In various exemplary, nonlimitingembodiments, the takedown pin 1500 comprises at least some of a head1510, a shank 1530 extending from the head 1510 to a terminal surface1534, an optional intermediate portion 1520, a first groove or slot 1540having an associated first detent recess 1542 and second detent recess1547, a second groove or slot 1550 having an associated first detentrecess 1552 and second detent recess 1557, and a connecting groove orslot 1560.

It should be appreciated that these elements correspond to and aresubstantially similar in form and/or function to the head 1010, theshank 1030 extending from the head 1010 to the terminal surface 1034,the optional intermediate portion 1020, the first groove or slot 1040having the associated first detent recess 1042 and second detent recess1047, the second groove or slot 1050 having the associated first detentrecess 1052 and second detent recess 1057, and the connecting groove orslot 1060, as described herein.

However, as illustrated in FIGS. 34A-34H, in certain illustrative,non-limiting embodiment(s) of the present disclosure, the projection1035 is not included and the second groove or slot 1450 extends to anopen or at least partially open end 1453. The open or at least partiallyopen end 1453 extends through the terminal surface 1434 of the shank1430.

In various exemplary embodiments, at least a portion of the open or atleast partially open end 1553 includes a ramped surface portion. Theramped surface portion may extend toward the outer surface of thetakedown pin 1500 or extend away from the outer surface of the takedownpin 1500, as the open or at least partially open end 1553 extends towardthe terminal surface 1534 of the shank 1530.

By extending the second groove or slot 1550 to an open or at leastpartially open end 1553, the takedown pin 1500 can be more easilyinstalled in or removed from a lower receiver 20 of a firearm 30.

In this manner, the takedown pin 1500 may optionally be installed orremoved from the lower receiver 20 in a nontraditional manner, withoutrequiring removal of the castle nut, buffer tube, and receiver end platefrom the lower receiver 20.

While the present disclosure has been described in conjunction with theexemplary embodiments outlined above, the foregoing description ofexemplary embodiments of the disclosure, as set forth above, areintended to be illustrative, not limiting and the fundamental disclosedsystems, methods, and/or apparatuses of the present disclosure shouldnot be considered to be necessarily so constrained. It is evident thatthe present disclosure is not limited to the particular variation setforth and many alternatives, adaptations modifications, and/orvariations will be apparent to those skilled in the art.

It is to be understood that the phraseology of terminology employedherein is for the purpose of description and not of limitation. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which the present disclosure belongs.

In addition, it is contemplated that any optional feature of theinventive variations described herein may be set forth and claimedindependently, or in combination with any one or more of the featuresdescribed herein.

Accordingly, the foregoing description of exemplary embodiments willreveal the general nature of the disclosure, such that others may, byapplying current knowledge, change, vary, modify, and/or adapt theseexemplary, non-limiting embodiments for various applications withoutdeparting from the spirit and scope of the disclosure and elements ormethods similar or equivalent to those described herein can be used inpracticing the present disclosure. Any and all such changes, variations,modifications, and/or adaptations should and are intended to becomprehended within the meaning and range of equivalents of thedisclosed exemplary embodiments and may be substituted without departingfrom the true spirit and scope of the disclosure.

Also, it is noted that as used herein and in the appended claims, thesingular forms “a”, “and”, “said”, and “the” include plural referentsunless the context clearly dictates otherwise. Conversely, it iscontemplated that the claims may be so-drafted to require singularelements or exclude any optional element indicated to be so here in thetext or drawings. This statement is intended to serve as antecedentbasis for use of such exclusive terminology as “solely”, “only”, and thelike in connection with the recitation of claim elements or the use of a“negative” claim limitation(s).

What is claimed is:
 1. A takedown pin, comprising: a head; a shank,wherein said shank extends, along a longitudinal axis, from said head toa terminal surface; a projection extending from at least a portion ofsaid terminal surface; a first groove or slot formed in at least aportion of said shank, wherein a first detent recess is formed proximatea first end of said first groove or slot, and wherein a second detentrecess is formed proximate a second end of said first groove or slot; asecond groove or slot formed in at least a portion of said shank,wherein a first detent recess is formed proximate a first end of saidsecond groove or slot, wherein a second detent recess is formedproximate a second end of said second groove or slot, wherein saidsecond end of said second groove or slot extends to an open or at leastpartially open end that extends through said terminal surface of saidshank and through at least a portion of said projection, and whereinsaid first end of said first groove or slot is positioned at a spacedapart location from said first end of said second groove or slot; and aconnecting groove or slot formed between said first end of said firstgroove or slot and said first end of said second groove or slot.
 2. Thetakedown pin of claim 1, wherein said first groove or slot defines anelongate, substantially linear first groove or slot that extends alongsaid longitudinal axis.
 3. The takedown pin of claim 1, wherein saidfirst groove or slot limits rotational movement and longitudinalmovement of said takedown pin, relative to a lower receiver.
 4. Thetakedown pin of claim 1, wherein if said takedown pin is appropriatelypositioned within a lower receiver of a firearm, a detent pin positionedat least partially within said first groove or slot interacts with saidfirst groove or slot so that said takedown pin can be repeatedly urgedbetween an engaged or locked position, wherein said firearm is operable,and a partially engaged or inoperably locked position, wherein saidfirearm is inoperable.
 5. The takedown pin of claim 1, wherein saidfirst detent recess of said first groove or slot is associated with anengaged or locked position and said second detent recess of said firstgroove or slot is associated with a partially engaged or inoperablylocked position.
 6. The takedown pin of claim 1, wherein said secondgroove or slot defines an elongate, substantially linear first groove orslot.
 7. The takedown pin of claim 1, wherein said second groove or slotdefines a substantially arcuate, second groove or slot.
 8. The takedownpin of claim 1, wherein said second groove or slot limits saidrotational movement of said takedown pin to 90°, on said longitudinalaxis of said shank.
 9. The takedown pin of claim 1, wherein if saidtakedown pin is appropriately positioned within a lower receiver of afirearm, a detent pin positioned at least partially within said secondgroove or slot interacts with said second groove or slot so that saidtakedown pin can be repeatedly urged between an engaged or lockedposition, wherein said firearm is operable, and a disengaged or unlockedposition, wherein said firearm is inoperable.
 10. The takedown pin ofclaim 1, wherein said first end of said first groove or slot ispositioned approximately 180° around said shank from said first end ofsaid second groove or slot.
 11. The takedown pin of claim 1, whereinsaid first end of said first groove or slot is positioned approximately90° around said shank from said first end of said second groove or slot.12. The takedown pin of claim 1, wherein said connecting groove or slotis formed so that said takedown pin can be rotated such that a detentpin can engage at least a portion of said connecting groove or slot totransition between said first groove or slot and said second groove orslot.
 13. The takedown pin of claim 1, wherein said projection includesan arcuate or semicircular surface portion.
 14. The takedown pin ofclaim 1, wherein said projection comprises a pin that extends from saidterminal surface of said shank.
 15. A takedown pin, comprising: a head;a shank, wherein said shank extends from said head to a terminalsurface; a first groove or slot formed in at least a portion of saidshank, wherein a first detent recess is formed proximate a first end ofsaid first groove or slot, and wherein a second detent recess is formedproximate a second end of said first groove or slot; a second groove orslot formed in at least a portion of said shank, wherein a first detentrecess is formed proximate a first end of said second groove or slot,wherein said second end of said second groove or slot extends to an openor at least partially open end that extends through said terminalsurface of said shank, and wherein said first end of said first grooveor slot is positioned at a spaced apart location from said first end ofsaid second groove or slot; and a connecting groove or slot formedbetween said first end of said first groove or slot and said first endof said second groove or slot.
 16. The takedown pin of claim 15, furthercomprising a projection extending from at least a portion of saidterminal surface.
 17. A takedown pin for a firearm, comprising: a head;a shank, wherein said shank extends from said head to a terminalsurface; a projection extending from at least a portion of said terminalsurface; a first groove or slot formed in at least a portion of saidshank, wherein a first detent recess is formed proximate a first end ofsaid first groove or slot, and wherein a second detent recess is formedproximate a second end of said first groove or slot; a second groove orslot formed in at least a portion of said shank, wherein said first endof said first groove or slot is positioned at a spaced apart locationfrom a first end of said second groove or slot; and a connecting grooveor slot formed between said first groove or slot and said second grooveor slot.
 18. The takedown pin of claim 17, wherein a detent recess isformed proximate said first end of said second groove or slot, andwherein a detent recess is formed proximate a second end of said secondgroove or slot.
 19. The takedown pin of claim 17, wherein said secondend of said first groove or slot extends to an open or at leastpartially open end that extends through said terminal surface of saidshank.
 20. The takedown pin of claim 17, wherein a second end of saidsecond groove or slot extends to an open or at least partially open endthat extends through said terminal surface of said shank and through atleast a portion of said projection.